Hydraulic jack



Patented May 31, 1938 UNITED STATES PATENT OFFICE HYDRAULIC JACK Timothy C. Pomeroy, Long Beach, Calif. Application December 23, 1935, Serial No. 55,874

6 Claims.

This invention relates to new and useful'improvements inhydraulic jacks, generally, and more particularly to jacks of the general character disclosed inmy Patent No. 1,744,673.

An object of the present invention is to provide a simple and eflicient hydraulic jack which may safely be carried about in the tool box of a vehicle without danger of leakage, regardless of temperature changes, A

A further object is to provide a hydraulic jack in which the usual breather duct, common to jacks of this character, has been eliminated, and which is so constructed that when once filled with an ample supply of oil, or other suitable pressure medium, it may be operated for a long period of time without having to replenish any of the pressure medium thereof. v

A further object is to provide ahydrauiic jack provided with an expansion chamber secured directly to the body of the jack, and having its lower end communicating with the upper end of the jack cylinder, whereby ,a portion of the fluidv contained in the expansion chamber is drawn into the jack cylinder, when the plunger is elevated, to thereby replace the fluid, which is normally displaced by the operating parts within the cylinder.

Other objects reside in thespecific construction of the sealing means for preventing leakage between the cylinder and plunger at the upper end of the jack, and in theoperating handle; in the specific construction of the plunger head, whereby it is practically impossible for any of the liquid to escape from beneath the plunger head into the upper portion of the cylinder; in the simplified construction of the valve mechanism; in the particular manner of mounting the expansion tank directly upon the body of the jack, whereby-it becomes in effect an integral part thereof; and, in the novel means detachably-secured to the plunger for engaging the vehicle or object to be lifted, which comprises a step mounted for vertical. adjustment, whereby it may be lowered to a position in close proximity to the ground for engaging a low object, and in'the pivotal mounting of said hanger upon the head of the plunger whereby said hanger may be rotated about a vertical axis with respect to the jack.

7 Other objects of the invention will appear from the following description and accompanying drawings and will be pointed out in the" annexed claims.

In the accompanying drawings, there has 'been' disclosed a structure designed to carry out the various objects of the invention, but it is to be understood that the invention is not confined to the exact features shown as various changes may be made within the scope of the claims which follow.

In the drawings: 5

Figure 1 is a vertical sectional view showing the general construction of the jack;

Figure 2 is a sectional plan view on the line 22 of Figure 1, with some of the parts shown in Figure 1 omitted;

Figure 3 is adetail sectional view on the line 3-3 of Figure 2;

Figure 4 is an enlarged detail sectional view showing the normal shape of the sealing means provided at the upper end of the cylinder;

Figure 5 is a/simil'ar view showing the sealing means when under pressure;

Figure 6 is a detail sectional view showing one of the metallic sealing members of the operating handle, removed therefrom; and

Figure 7 is a top view of the jackon a smaller scale, showing the lifting hanger disposed at an angle to the jack handle.

In the selected embodiment of the invention here shown, there is illustrated in Figure 1, for 25 purposes of disclosure, a hydraulic jack of' the general character shown and described in my patent, hereinbefore mentioned, comprising a cylinder H mounted in-a suitable base l2.

A hollow plunger I4 is mounted within the cyl- 3o inder I I and has its wall spaced from the wall of the cylinder to provide an annular fluid chamber IS. The plunger is provided at its lower end with a head, generally indicated by the numeral l6, and comprising a cap i1 having a reduced portion I8 fitting into the lower end of the plunger l4 and suitablysecured thereto, as by welding.

A suitable lifting head I9 is secured to the upper end of the plunger l4 and has a reduced por- 40 tion 2| fitting into the upper end of the plunger, as clearly illustrated in Figure 1. The head .19 is preferably secured to the plunger by welding in a manner similar to the lower head or cap ll. Discharge and intake tubes 22 and 23, respectively, are arranged in spaced relation within the plunger I4, and have their upper ends secured to the head l9 by suitable threads, as shown, or, if desired, they may be secured thereto by welding. The lower ends of the tubes 22 and 23 pass through suitable apertures provided in the cap ,II and extend below the latter, as clearly illustrated in Figure 1. p

A feature of the invention resides in the construction of the plunger head It, which, as best to provide the plunger head l6.

shown in Figure 1, comprises a suitable leather cup or packing 24, seated against the lower face of the cap l1 and having aperturestherein for receiving the terminals of the tubes 22 and 23. A plurality of resilient cup-shaped disks 25, of a suitable material such as copper, are nested together and seated against the packing 24. A plate or washer 28 is seated directly against the inner cup-shaped disk' 25, and has openings therein for receiving the terminals of the tubes 22 and 23. The lower ends of the tubes project below the plate 26 and have suitable nuts or collars 21 secured thereto, as by welding, whereby the leather cup or packing 24, cup-shaped disks 25, and the plate 25 are suitably secured together Before securing the nuts or collars 21 to the tubes 22 and 23, pressure is applied to the plate 26 to thereby tightly compress the parts 24 and 25 between it and the cap l1, whereby a very substantial structure or plunger head is provided.

The lower end of .the intake tube 23 is closed bymeans pf a suitable plug 28, preferably welded thereto. This plug is shown projecting below the terminals of the tubes 22 and 23, whereby it may engage a plate 38 provided in the lower end of the cylinder H, to thereby limit the downward movement of the plunger in the cylinder. The cup-shaped disks 25 are shaped to constantly exert an outward pressure against the annular flange of the packing 24 to thereby hold it in leakproof engagement with the wall of the cylinder, as will readily be understood by reference to Figure 1. .7

Suitable openings. 29 and 3| are provided in the-tubes 23 and 22, respectively, adjacent to the plunger head I6, and are substantially hor'izontally alined, as shown. The opening 3| establishes communication between the interior of-the plunger l4 and the annular chamber IS in the cylinder above the plunger head I 6; and the opening 29 establishes communication between the interior of the plunger and the tube 23.

Another feature of the invention resides in the means provided at the upper end of the jack for closing the gap between thewall of the cylinder and the wall of the plunger. Hydraulic jacks of the character herein disclosed, are often subjected to very' high pressures, and meansmust therefore be provided for positively preventing leakage of the fluid from the jack while in operation and while supporting a load. A common source of trouble in hydraulic jacks resides in the difliculty experienced in preventing leakage of the oil or liquid from the upper end of the cylinder, and to eliminate .this difficulty, I employ a novel packing or sealing means. for closing the gap between the wall of the plunger and the upper end of the cylinder, whereby leakage is substantially elimiriated, even when the jack is supporting a heavy load for a long period of timel l This novel packing, as best 4, and 5, comprises a suitable annular packing ring 32, of a suitable material such, for example, as vegetable rubber, which 'I have .found, does not readily deteriorate when subjected to pressureliquids, such as oil, commonly used in jacks of this general character. The packing 32 is fitted between two annular metallic sealing members 33 and 34 of a suitable spring metal, having convex annular portions 35, as best shown in Figures 4 and 5. A guide ring 36 is fitted into the upper .end of the cylinder II and has a beveled face 31 seated against a correspondingly beveled face provided on theupper end of the cylinder wall.

- shown in Figures 1,

The guide ring or collar 35 iswelded in place,

whereby it becomes, in effect, an integral part of retained thereon by a cap 38, preferably received in threaded engagement with the upper end of the cylinder II. This cap may, if desired, be welded directly to the wall of the cylinder. When tween the edges of the flanges of the sealingrin'gs,

into engagement with the wall of the plunger and the adjacent wall of the cap 38. When the above described sealing means is thus compressed, the liquid in the annular chamber I5 cannot escape therefrom to the atmosphere, when the jack is subjected to aheavy load. I

Figure 5 shows the positions which thepacking ring 32 and sealing rings 33 and 34 tend to assume, when pressure is applied to the top and bottom thereof, when positioned in the jack. When the sealing means is thus compressed, the flanges of the sealing rings 33 and 34 are pressed into the cap 38 is forced downwardly against. the packing 32, the convex portions 35 of the sealingrings 33 and 34 are engaged directly by the guide leak-proof engagement with the walls of the plunger l4 and cap 38, as clearly illustrated in Figure 1.

a The lifting head'l8 is shown fcomprising a pair of check valves 39 and 4|, mounted in suitable valve chambers, 42 and 43, respectively. The valve 39 is normally held in engagement with a seat 44 by the action of a spring 45, retained in the valve chamber by a suitable plug 45. The valve 4| is. normally held in engagement with. a seat 41 by gravity. The valve chamber 42 is in direct communication with the discharge tube 22 by means of 'a duct 48, and the valve chamber 43 communicates with the intake tube 23 through a duct 49.- The valve chambers 42 and 43 are in direct communication with each other through a port 5|. I

To operate the jack, the fluid within the plunger and in the annular fluid.;chamber I5, is pumped into the lower end of the cylinder below the plunger head l8, whereby the plunger is relatively moved upwardly in the cylinder. The means for thus "pumping the fluid into the lower 'portionof the cylinder is shown comprising a suitable displacement rod 52, mounted in a tubular handlesec tion 53 and having a head 54' fitting the bore in the handle section 53. The handle section 53 is pivotally connected to another handle section 55 by a suitable swivel joint, generally indicated by the numeral 50, which is similar in construction tothe one disclosed 'in my patent, hereinbefore referred to.

The handle section 55 is pivotally connected to seated in a tapered bore 51, as best shown in the lifting head I9 by a suitable plug valve 58', v

Figure .2. The plug'valve 56v is retained in the bore 51 by a suitable securing me'ans, generally .a port 63.

indicated by the numeral 58. This securing means is similar to that shown in my above mentioned patent, and automatically takes up wear in the valve to thereby prevent leakage.

The plug valve 56 has a peripheral groove 59, which is alined with a port 6| communicating with the valve chamber 43, as best shown in Figure 1. The plug valve 56 also has a fluid circulating duct 62 which communicates at one end with the peripheral groove 59 by means of The opposite end of the duct 62 is in direct communication with the interior of the handle section 55, whereby direct communication is established between the peripheral groove 59 and the interior of the handle section 53, as will be clearly understood by reference to Figuresil and 2.

Another important feature of the invention resides in the means provided for preventing leakage of the oil or liquid from the handle section 53 around the stem 62 of the displacement rod 52. This stem, it will be noted by reference to Figure 1, is provided with a hand grip 65, whereby it may be conveniently reciprocated within the handle section 53 when the jack is manipulated.

The novel means provided for preventing leakage of the oil around the displacement rod 62 is somewhat similar in construction to the sealing means at the upper end of the cylinder, and comprises a suitable packing ring 66, interposed between two sealing rings 61 and ,68. The lower sealing ring 68 is seated upon a supporting member 69 provided in the grip portion H of the handle section 53. A suitable collar or washer 72 engages the upper sealingring' 61, and is constantly pressed thereagainst by the action of a compression spring 13, having one endengaging the collar 12 and its opposite end the upper wall 14 of the grip portion H of the handle section 53.

The axial flanges of the sealing rings 61 and 68 of the packing 66 are preferably provided with a plurality of small slits 15 '(see Figure 6), to thereby render said rings more flexible andresilient in operation, and whereby thractlon of the spring 13 may compress the packing 66 sufficiently to cause the flanges 61 and 68 -to be constantly pressed against the walls oi the displacement rod 52. and the bore of the grip por tion 1| The means for unseating the valves 39 and 4| is similar to that shown and described in my previously mentioned patent, and briefly consists of a pair of thrust members 16 and 11, the former having one end adapted to engage the valve 39, and the latter having one end adapted to engage the valve M. The opposite ends of the thrust members 16 and I! are constantly held in engagement with the periphery if the plug valve 56 by suitable compression ;prlngs l8 and 19, respectively, as clearly illus- ;rated in Figure 1.

The thrust members 16 and 11 are arranged,'

me over the other, in the lifting head I9, and

ire alincd with the peripheral groove.59 in the alug valve 56. One end of the groove 59 terninates in cam faces 8| adapted to engage the hrust members 16 and 11 to thereby actuate he latter. When the operating handle of the ack, comprising the sections 53 and 55, is in he position shown in Figure 1, that portion of he periphery of the plug valve 56 which is dis nosed between the cam face 8| and the end vall 82 of the groove 59, will be in engagement with the thrust members 16 and 11, whereby the latter are actuated to unseat the valves 39 and M, as clearly illustrated in Figure 1.

When the valves are thus positioned, direct communication is established between the interior of the plunger I4 and the lower end of the cylinder, below the plunger head l6, whereby the plunger may readily be lowered to its lowermost position, as shown in Figure 1. When the valves are so positioned, the oil or liquid in the cylinder below the piston, and which is supporting the load, will flow upwardly through the discharge tube 22, through the open valves 39 and 4|, thence downwardly through the intake tube 23, and through the opening 29 thereof, and back to the interior of the plunger, thereby permitting the plunger to descend into the cylinder. When the operating handle is swung outwardly to a position whereby the heads of the thrust members I6 and 11 will engage the bottom of the peripheral groove 59 of the plug valve, and the displacement rod 52-is reciprocated within the handle section 53, the oil is drawn upwardly from the interior of the plunger through the tube 23, check valve 4|, thence through the unseated valve 39, and downwardly through the tube 22 into the cylinder below the plunger head [6. Such circulation of the oil or liquid will cause the plunger to be elevated in the cylinder, as will readily be understood.

Another important feature of this invention resides in mounting directly upon the wall of the cylinder, an expansion tank 83, which contains a reserve quantity of liquid to thereby positively prevent the jack from becoming inoperative, as a result of an insuflicient supply of pressure liquid.

The expansion tank 83 is best shown in Figure 1, and is hermetically sealed at its upper and lower ends by suitable caps 84 and 85, respectively, which preferably are welded to the wall of the expansion tank. The tank, as a whole, is secured to the wall of the cylinder, preferably by welding. whereby it becomes, in effect, an integral part thereof. A small tube 86 is secured in piacc within the expansion chamber 81, defined by the walls of the tank 83, and is shown having its upper end bent at right angles and passing through an opening in the wall of theexpansion chamber and through an opening in the wall of the cylinder, whereby the tube 86 is in direct communication with the annular fluid chamber I of the cylinder. The joints between the tube 86 and the walls of the expan sion chamber 31 and cylinder are hermetically I sealed to prevent leakage therebetween. The other end of the tube 86 terminates adjacent to the bottom wall 65 of the expansion chamber and is preferably bent outwardly, as shown, although it is to be understood that the lower end of the tube 86 may be otherwise shaped, if desired. i

One of the distinguishing features of the construction ofthe expansion tank, herein disclosed, over structures of this general character now in use, resides in the size of the expansion tank, whereby a relatively large chamber is provided above the level of the liquid therein,'as clearly illustrated in Figure 1. By enlarging the size of the expansion tank, as herein disclosed, I have found that the usual breather or vent hole, commonly provided in hydraulic jacks, may be dispensed with, and I have also found that the usual filler plug may be eliminated or, if such a plug is provided, it may be locked in sealing position so that it cannot readily be removed from the jack. Because of the size of the expansion chamber 81 above the level of the oil therein, when the jack is operated to lift a load, a portion of the oilin the expansion chamber may readily be drawn through the tube 86 into the cylinder to supply the oil displaced by the wall of the plunger .and the tubes 22 and23 in the plunger, When a portion of the oilin the expansion chamber'is thus drawn into the cylinder, a vacuum tends to 'develop in the expansion chamber 81, but, be-

cause of the size of this chamber, and further, because of the limited amount of oil withdrawn from the expansion chamber, the vacuum thus developed is not sufficient to interfere with the the expansion chamber 81, as herein stated, the

jack, as a whole, is rendered far more flexible in operation andis more fool-proof in that it cannot readily be overcharged with oil, which might occur if an inexperienced person should introduce oil into the jack.. Also, by securing the expansion tank 83 directly to the cylinder, it may be so fixed thereto, that it cannot readily be jarred loose, which might cause leakage and thereby render the expansion tank inoperative. To secure the expansion tank directly-to the cylinder, therefore, is an important" feature of the invention.

Means is also provided whereby the jack may readily be used for lifting objects varying considerably in height. Such means is clearly'illustrated in Figure 1, and comprises a hanger 88 having its upper end portion 89 pivotally secured to the lifting head H. of the plunger, by such means as a shouldered stud 9|. If necessary, the stud may be locked in place by a suitable pin 90. The hanger 88 is provided with suitable ratchet teeth, generally indicated by the numeral .92,

adapted to be adjustably engaged by a step, generally indicated by the numeral 93. This step is slidably mounted upon the upright portion of the hanger 88 and may readily be vertically adjusted thereon by simply swinging the lower end thereof outwardly, as indicated by the dotted lines in Figure 1, whereby the step may be moved up or down, as desired. When the step isreturned to its normal horizontal position, as shown in full lines inIFigure 1, it lockingly engages the ratchet teeth 92, whereby it may be inserted under an object or a load to lift the latter when the jack is operated. The lower end of the hanger 88 is supported by a suitable antifriction roller 94, whichpreferably has a concaved' periphery; and is adapted to roll directly upon the wall of the cylinder, as clearly shown. A rib is shown provided upon the hanger adjacent its upper end adapted to bear against the wall of the plunger thereby to further support the hanger.

By thus pivotally supporting the hanger upon the plunger, it may be relatively rotated about a vertical axis, with respect to the operating handle 58-54, as illustrated in Figure 7.- This is a very "desirable feature'as it makes it possible to insert the jack under an automobile axle in close proximity to a wheel thereof, with the jack handle disposed at an angle to theaxle, whereby said handle may be conveniently operated without interference from the usual wheel fenders.

Means is also provided within theplunger for preventing excessive pressures being developedin the jack, when in operation, and consistsof arelief valve, generally indicated by the numeral 95, and provided in the plunger head l6. This relief valve has an operating stem 96, shown provided with a cross bar 91 having its terminals projecting outwardly through suitable elongated openings 98 in the wall of the plunger l4, whereby the terminals of the rod 91 will engage the guide ring 36, when the plunger reaches a predetermined elevation, thereby automatically opening the relief valve 95. Such opening of the relief .valve will permit the oil being pumped into the cylinder below the plunger head IE to bypass through the plunger head l6, back into the interior of the plunger. The relief valve 95 is shown and described in detail in my Patent No. 1,699,917, and it is therefore thought unnecessary to further illustrate and describe the same .herein. The novel jack herein disclosed, has been found very efilcient and practical in actual operation. Because of the unique construction 'of the plunger head I6 and also as a result of the provision of the expansion tank 83, the jack may be filled with the necessary supply of oil or pressure liquid and suitably sealed, before leaving the factory, whereby it cannot be tampered with by inexperienced persons. Thus, the manufacturer willbe assured that the jack will always operate ef-,- ficiently unless, of course, it should become damaged as a result of rough usage and handling, which might be of sufllcient scope to cause leakage. I The novel sealing means, shown in Figures 4 and 5, so seals the jack against leakage, that it becomes substantially leak-proof, whereby all joints in the jack may be welded, with the result that the jack, as a whole, may be made from lighter material such, for example, as tubular and plate steel, or any other suitable plate material which is comparatively lighter in weight than cast metal. Because of the size of the expansion chamber 81, the jack may also be used in extremely hot temperatures without danger,

.as the oil'or liquid has ample room to expand and contract without, in any way, jeopardizing the operation of the jack. I claim as my invention;

1'. In a hydraulic jack, a cylinder, a hollow plunger therein having means atits upper end for engaging an object to be lifted, a head at the lower end of the plunger engaging the wall of the cylinder, an inelastic fluid in the cylinder and plunger, means for circulating said fluid to operate the plunger,-.and an expansion tank mounted in fixed relation with respect tothe cylinder and having means for establishing communication between the lower end thereof and the upper portionof the cylinder. 7 1

2. In a hydraulic jack, a cylinder, a 110110 plunger therein having means at its upper end for engaging an object to be lifted, a head a1 the lower end of the plunger engaging the wali of the cylinder, an inelastic fluid in the cylindei and plunger, a valve mechanism in the uppei end of the plunger, a;pump.pivotally connecte to the plunger for operating said valve mechanism to circulate theifluld'between the plunge] and cylinder to thereby operate the plunger, a! expansiontank mount d in fixed relation witl respect to the cylinder, and a conduit connecting the interior of the lower end of the expansion tank with the upper portion 01' the cylinder.

3. In a hydraulic jack, a cylinder, a hollow plunger therein having a lifting head at its upper end for engaging an object to be lifted, means at the lower end of the plunger engaging the wall of the cylinder in leak-tight relation, an expansion chamber of largeproportions disposed in fixed relation to the cylinder, said chamher being sealed to the atmosphere, and means establishing communication between the lower end'of the expansion chamber and the upper end of the cylinder whereby additional fluid may be drawn into the cylinder from said chamber, when the plunger is operated, and said additional fluid being returned to the expansion chamber when the plunger islowered to its normal position.

4. In a hydraulic jack, a cylinder, a hollow plunger therein having a lifting head at its upper end for engaging an object to be lifted, means at the lower end of the plunger engaging the wall of the cylinder in leak-tight relation, and an expansion chamber disposed in fixed relation to the-cylinder and having means establishing communication between the. lower end thereof and the upper end of the cylinder, said expansion chamber containing an additional supply of fluid, a portion of which is drawn into the cylinder when the plunger is elevated, and which fluid is returned to the expansion chamber when ,being drawn into the jack when the plunger is lowered to its normal position, said expansion chamber being sealed to the atmosphere and of such size that the vacuum and pressure created therein by the reciprocal move- ,ment of the plunger in the cylinder, will not eifect the operation of the plunger, and whereby the jack will not require a breather or vent duct,-

thereby'preventing grit, dust, and moisture from the latter is operated.

5. In a hydraulic jack, a cylinder, a plunger therein having means at its upper end for engaging an object to be lifted, an inelastic fluid in the cylinder, means for circulating said fluid to operate the plunger, an expansion tank mounted in fixed relation with respect tothe cylinder, and means for establishing communication between the lower end of the expansion tank and the upper portion of the cylinder.

6. In a hydraulic jack, a cylinder, a plunger therein having meansat its upper end for engaging an object to be lifted, an inelastic fluid in the cylinder, a valve mechanism in the upper end of the plunger, a pump pivotally connected to the plunger for operating said valve mechanism to circulate the fluid between the plunger and cylinder, thereby to operate the plunger, an expansion tank mounted in fixed relation with respect to the cylinder, and a conduit connecting the interior of thelower end of the expan--' sion tank with the upper portion of the cylinder.

, TIMOTHY C.v POMEROY. 

